concurrency

A typeclass abstraction over much of Control.Concurrent (and some
extras!). If you’re looking for a general introduction to Haskell
concurrency, you should check out the excellent Parallel and
Concurrent Programming in Haskell, by Simon Marlow. If you
are already familiar with concurrent Haskell, just change all the
imports from Control.Concurrent.* to Control.Concurrent.Classy.* and
fix the type errors.

A brief list of supported functionality:

Threads: both unbound and bound.

Getting and setting capablities.

Yielding and delaying.

Mutable state: STM, MVar, and IORef.

Atomic compare-and-swap for IORef.

Exceptions.

All of the data structures in Control.Concurrent.* and
Control.Concurrent.STM.* have typeclass-abstracted equivalents.

A reimplementation of the async package, providing a
higher-level interface over threads, allowing users to conveniently
run MonadConc operations asynchronously and wait for their
results.

This is quite a rich set of functionality, although it is not
complete. If there is something else you need, file an issue!

This used to be part of dejafu, but with the dejafu-0.4.0.0 release,
it was split out into its own package.

Why this and not something else?

Why not base: like lifted-base, concurrency uses typeclasses to
make function types more generic. This automatically eliminates
calls to lift in many cases, resulting in clearer and simpler
code.

Why not lifted-base: fundamentally, lifted-base is still using
actual threads and actual mutable variables. When using a
concurrency-specific typeclass, this isn’t necessarily the case. The
dejafu library provides non-IO-based implementations to allow
testing concurrent programs.

Why not IOSpec: IOSpec provides many of the operations this
library does, however it uses a free monad to do so, which has extra
allocation overhead. Furthermore, it does not expose enough of the
internals in order to accurately test real-execution semantics, such
as relaxed memory.

Contributing

Bug reports, pull requests, and comments are very welcome!

Feel free to contact me on GitHub, through IRC (#haskell on freenode),
or email (mike@barrucadu.co.uk).

Changes

Release Notes=============

This project is versioned according to the PVP_, the *de facto*standard Haskell versioning scheme.